Thermodynamics of the polymerisation of polyglycerols in an acidic and micellar environment

Santos, Vadilson Malaquias dos; Uliana, Fabricio; Lima, Rayanne Penha Wandenkolken; Silva Filho, Eloi Alves da

doi:10.1590/0104-1428.20220110

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ORIGINAL ARTICLE • Polímeros 34 (1) • 2024 • https://doi.org/10.1590/0104-1428.20220110 copy

Thermodynamics of the polymerisation of polyglycerols in an acidic and micellar environment

Authorship SCIMAGO INSTITUTIONS RANKINGS

Abstract

This work consisted of studying polyglycerols in an acidic and micellar environment. The effects on surface tension, micellisation, and the Gibbs free energy of interface liquid-liquid (w/o) for directing the etherification of monomer glycerol with n-hexanol, n-octanol, n-decanol, n-dodecanol, and micellar solutions of sodium dodecylsulfate and dodecylbenzenesulfonic acid were studied at 70, 90 and 130°C . Polyglycerols with low weights and prepolymers were obtained. Theoretical methods such as density functional theory and molecular dynamics simulations were used to examine the effects of surface tension, the conformations of glycerol, and the position of the hydroxyl group of alcohols. A theoretical analysis (DFT/B3LYP) of the potential energy surface of glycerol and alcohols allowed finding stable conformations of the molecule, differing in the relative arrangement of hydroxyl groups. Our results helped achieve a better understanding of the interaction complex process of surfactant/catalyst of glycerol reactions in biphasic systems.

Keywords:
hydroxyl groups; liquid systems; surfactants

Name	Reaction conditions	Molecular weight (g/mol)	Viscosity (mPa.s) 20 ºC	hydroxyl value (mg.KOH/g)
GLY	Pure	92	1,412	1,829
PG1	DBSA/DO1/H⁺/130ºC/24h	3,880	10,893	684
PG2	SDS/OCT1/H⁺/ZnCl₂/70ºC/20h	2,556	7,730	903
PG3	SDS/DO1/H⁺/FeCl₂/90ºC /24h	3,280	9,893	920

Isotherm (^oC)	CMC (mmol/L) ± 0.5	S₁	S₂	α ± 0.02		n
25	7.20	67991	22041	0.324	0.676	69.02
35	7.72	63987	23281	0.364	0.636	64.20
45	8.32	67244	25268	0.378	0.624	55.10
55	8.93	67833	31985	0.471	0.528	47.63
65	9.91	68996	30839	0.447	0.553	40.11

Isotherm (^oC)	CMC (mmol/L) ± 0.3	S₁	S₂	α ± 0.04	β	n
10	36.9	276.0	551.9	0.50	0.50	104
20	37.5	397.0	554.0	0.72	0.28	98
30	37.8	464.9	562.8	0.82	0.18	93
40	38.6	384.8	577.3	0.66	0.34	87
50	39.1	520.5	598.8	0.87	0.13	82

Temperature (ºC)	Water	Water/SDS	Water/DBSA	Interface tension
25	71.9	33.5	41.5	29.0
35	74.1	32.6	30.4	28.7
45	68.7	32.6	32.1	17.6
55	67.1	31.9	32.7	17.4
65	65.3	31.5	31.8	16.2
70	64.5	31.4	32.5	15.8

System	Pure	SDS	SDS/GLY	SDS/PGs	PG/GLY	PG
Water/HEX1	18.76	29.59	18.38	16.29	16.05	15.32
Water/OCT1	19.0	18.5	19.2	18.4	19.2	20.5
Water/DO1	29.0	33.5	24.1	23.0	29.3	28.4

Properties	DBSA	SDS	HEX1	OCT1	DEC1	DO1
HOMO $(eV)$	$- 1.575$	$- 1.792$	$- 7.435$	$- 7.434$	$- 7.364$	$- 7.430$
LUMO $(eV)$	$2.512$	$2.736$	$0.848$	$0.806$	$0.753$	$0.834$
$E_{g} (eV)$	$4.087$	$4.528$	$8.283$	$8.240$	$8.117$	$8.264$
χ $(eV)$	$- 0.469$	$- 0.472$	$3.294$	$3.314$	$3.306$	$3.298$
μ $(eV)$	$0.469$	$0.472$	$- 3.294$	$- 3.314$	$- 3.306$	$- 3.298$
η $(eV)$	$2.044$	$2.264$	$4.142$	$4.120$	$4.059$	$4.132$
s $(eV)$	$0.245$	$0.221$	$0.121$	$0.121$	$0.123$	$0.121$
ω $(eV)$	$0.054$	$0.049$	$1.310$	$1.333$	$1.346$	$1.316$
σ $(eV)$	$0.489$	$0.442$	$0.241$	$0.243$	$0.246$	$0.242$

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